textproduct: Albany

WHAT HAS CHANGED

Increased expected high temperatures this afternoon and again tomorrow due to anomalously warm airmass overhead and plenty of sunshine. Lowered overnight lows tonight, and Monday for the eastern slopes of the ADKs and CT River Valley. Added patchy fog into the forecast for tonight. Also trimmed back PoPs south and east of the Capital District Wednesday afternoon. Finally, ice jam flood threat looks to be declining, but still monitoring potential river rises this week due to snowmelt and rain later this week with a cold frontal passage.

KEY MESSAGES

1) Above normal temperatures expected into midweek for the entire forecast area. The anomalous warmth along with mid-week rain will result in increased snowmelt and runoff. Rises are expected on area rivers, creeks, and streams, with a low to medium chance for minor river flooding.

2) A strong storm system is expected to bring gusty winds for Wednesday night into Thursday. As the storm passes through the region, rapidly dropping temperatures and rain ending as wet snow are expected across the region.

3) Colder for the end of the week into next weekend with a couple additional chances for precipitation..

DISCUSSION

KEY MESSAGE 1...

As of 1:55 PM EDT...Our region is currently in an area of deep SW flow, which is resulting in low to mid-level warm advection. With mainly clear skies and some gusty winds of 15-20 kt, daytime mixing has allowed temperatures to climb into the 60s for many valley areas per latest ASOS and NYS mesonet obs. This is a few to several degrees above NBM guidance. Dew points also running several (in some cases 10+) degrees below NBM guidance, so these changes were made as well. Diminishing winds and continued clear skies overnight tonight will again allow for favorable radiational cooling conditions, and we could therefore see some patchy radiation fog develop again tonight, especially with lows and dew points a few degrees warmer than last night. However, temperatures tomorrow again warm back into the 60s for valley areas, possibly to the low 70s for the Mid Hudson Valley and southern Litchfield County, despite a few more clouds around compared to today. Increasing clouds Tuesday night will keep low temperatures warmer mainly in the upper 30s to mid 40s.

Wednesday, northern and southern stream systems phase over the center of the country, with a deepening sfc low tracking to our west through the Great Lakes. This will help lift a warm front northwards through the region, with 850 mb temps increasing to +12 to +14C. It will likely take the warm front longer than modeled to lift north with a retreating 1030+ mb sfc high to the N/NE, but southern and western areas will likely once again see temperatures well into the 60s. For portions of the upper Hudson Valley/east slopes of the ADKs and CT River Valley in VT, however, there is a pretty strong CAD signature, so we lowered temperatures here by blending in some of the NAM in coordination with BTV and GYX. Some showers are possible Wednesday for our far northern zones, closer to the mid-level warm front, but most of the region should generally remain dry through the day, especially south and east of Albany with the cold frontal passage not until Wednesday evening or night.

With the unusually warm temperatures, we will continue to see considerable snowmelt over the next few days. The deepest snowpack is across the ADKs and southern Greens where there remains as much as 6-8" of liquid in the snowpack, but these areas will be relatively cooler compared to the rest of the region. While we are certainly expecting some snowmelt here, the snowpack may compress further before more significant runoff from snowmelt occurs so confidence on flood potential here is rather low. Even still, the NERFC is expecting minor flooding on the Mohawk River at Delta Dam, and the West Canada Creek, with the Sacandaga River potentially approaching minor flood stage Thursday. For the rest of the region, many valley areas have lost much of their snowpack, but the Catskills, Mohawk Valley, and western MA/CT still have up to a couple inches of liquid in the snowpack. While more of the snow will likely melt in these areas, there is overall less liquid in the snowpack. So, while river rises are expected, the probability of minor flooding looks relatively low at this time except for on the Housatonic where there some minor flooding is remains possible.

The greatest river rises are expected Wednesday evening into Thursday, when there will be contribution to runoff not just from snowmelt, but from rain with the cold frontal passage. This is when the best chance for minor flooding will be. Will mention that with an overnight timing of the frontal passage, QPF has trended down slightly across the region (more details in Key Message 2, below), with most areas now expected to see under a half inch with even less across our southeastern zones. The reduced QPF may prevent more widespread flooding issues that we were worried about previously, especially south and east of the Capital District where QPF amounts may end up under a quarter inch.

Finally, will mention potential for isolated ice jam issues, mainly in the Mohawk Valley and/or ADKs over the next couple days. We have received reports of ice on the Mohawk River between Lock 6 and Lock 8 this morning, with some minor flooding of low-lying areas near the river. Fortunately, warming temperatures should help to melt some of the river ice over the next few days, so otherwise potential for additional ice jam issues looks fairly low.

KEY MESSAGE 2...

As the sfc low deepens to our west, S/SE winds become gusty on Wednesday. Then, Wednesday night into Thursday morning, the system's cold front tracks through the region as the sfc low tracks through southern Canada. Strengthening SW LLJ with a connection to the gulf will allow PWATs to climb to over 1.25", which is +3-4 sigma per the latest NAEFS. However, the best upper forcing will remain to the west of our area and lag behind the sfc cold front, although low- level convergence along the front does look fairly impressive. Will likely see a cold frontal rainband with some embedded rumbles of thunder (model forecast soundings show some limited instability, mainly south of I-90) track through the region Wednesday night into early Thursday AM. With a much colder airmass moving into the region behind the front, precipitation could end as some wet snow, although accumulations look minimal. Winds become gusty behind the front Thursday, with cold advection and deep mixing in the post-frontal regime. Some lake effect snow showers are possible across the western ADKs as well. Falling temperatures behind the front should put an end to snowmelt, but rivers continue to rise into Thursday as the runoff makes its way into the rivers and streams.

KEY MESSAGE 3...

Thursday night into Friday looks cool (lows in the 20s) as high pressure builds overhead. Then, Friday or Friday night, a clipper system approaching from the NW will bring additional precipitation chances. Still some uncertainty on the storm track this far out, but a track further south would allow for some snow/snow showers across the region, while a track further north would result in less precip overall and keep the snow confined to mainly high terrain areas. Any snow amounts generally look to be on the light side. We remain cool Saturday behind the clipper. Then, Sunday, another storm system will likely track to our west, but its approaching warm front may bring some additional rain/snow to the region. Low confidence in the overall track and evolution of this system at this time, but will continue to monitor over the next several days.

AVIATION /18Z MONDAY THROUGH SATURDAY/

VFR conditions will prevail through the afternoon with south/southwest winds around 10 knots with periods of gusts up to 20 knots. Surface winds are expected to decouple during the early evening hours which combined with a 30-40 knot low level jet will support the potential for periods of LLWS from KALB/KPSF northward through roughly 06Z. The combination of light winds and calm skies will also support the development of areas of valley fog tonight. KGFL and KPSF will have a medium chance of at least TEMPO, if not prevailing, IFR visibility restrictions during the 07Z-12Z timeframe tonight. Confidence is lower for prolonged visibility restrictions at KALB so TEMPO/PROB30 groups were not included with the current TAF package.

Outlook...

Tuesday Night: Low Operational Impact. Slight Chance of SHRA...FG. Wednesday: High Operational Impact. Breezy. Likely SHRA. Wednesday Night: High Operational Impact. Breezy. Definite SHRA. Thursday: Moderate Operational Impact. Windy With Gusts To 32 kts. Chance of SHRA...SHSN. Thursday Night: Low Operational Impact. Breezy. NO SIG WX. Friday: Moderate Operational Impact. Breezy. Chance of RA...SN. Friday Night: High Operational Impact. Breezy. Likely RA...SN. Saturday: Low Operational Impact. Breezy. Slight Chance of RA...SN.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.